Drill bit



Feb. 21, 1950 I 5. CREEL 2,498,251

DRILL BIT Filed Jan. 19, 1948 Fzgi IN VEN TOR.

23 265? 5. Cree Z A TTORAIE) Patented Feb. 21, 1950 UNITED STATES"PATENT OFFICE DRILL BIT Ernest S. Creel, Houston, Tex.

Application January 19, 1948, Serial No. 3,132'

3 Claims. 1

My invention relates to drill bits and more particularly to detachable bits for rotary drills.

The drill bits used heretofore consist generally of one solid piece of steel weighing seven or eight pounds and are usually threadedly connected with the lower end portion of the drill stem. The main object of my invention is to provide a drill bit consisting of a drill head adapted to be threadedly secured to the drill stern by means of a bit sub and a plurality of bit blades adapted to be removably secured to the bit head, so that it will not be necessary to remove the entire bit, when one or more of the blades should break or get dull, but that only the damaged blades need to be removed for sharpening or replacement, saving time and labor, shipping space, shipping cost, etc.

Other objects of my invention not specifically mentioned may appear in the following specification describing my invention with reference to the accompanying drawing illustrating a preferred embodiment of my invention. It is, however, to be understood, that my invention is not to be limited or restricted to the exact construction and combination of parts described in the I specification and shown in the drawing, but that such changes and modifications may be made, which fall within the scope of the claims appended hereto.

In the several figures of the drawing, similar parts are designated by similar reference characters and Figure 1 is a view partly in section and partly in elevation illustrating a bit constructed in accordance with an embodiment of the invention and in applied position;

Figure 2 is a view in bottom plan of the head of the bit as herein comprised;

Figure 3 is a view partly in section and partly in elevation of the bit blade support, showing one blade thereon and partly in section; and

Figure 4 is a view in perspective of one of the bit blades unapplied.

The drill bit B forming the subject matter of my invention comprises a hollow cylindrical blade support body ID, the upper end portion of which is provided with a male thread II adapted to engage a female thread I2 in a tubular coupling or bit sub I3, which in turn is adapted to be removably secured onto the lower end of a drill pipe or stem I4 of a rotary drill. The lower end surface I5 of the bit sub i3 is beveled inwardly for a purpose to be described later.

On the lower end portion of the support body ID, a substantially semi-globular head I6 is formed, the upper surface of which extends circumferentially beyond the support body It and is beveled inwardly as indicated at IT for a purpose to be described later. On the semi-globular surface of the head I6, three outwardly projecting shoulders I8 are formed extending at relative to each other and having vertical bit blade backing surfaces I9 facing in clockwise direction. Adjacent each blade backing surface a slot is ground into the head I5 forming a vertical rear surface 20 and a horizontal top surface 2i, and three holes 22 are provided extending through the head It and communicating with the bore 23 in the cylindrical body I0.

Three bit blades D are provided and each of them comprises a transversely arcuate plate 24 adapted to fit snugly around one third of the circumferential surface of the blade support body Ill above the head I6. The top edge of the plate 24 is beveled outwardly as at 25 at an angle to fit into the inwardly beveled lower edge surface i5 of the bit sub I3. The lower edge 26 of the arcuate plate 24 is beveled, as at 26, to fit into the inwardly beveled upper surface ll of the semi-globular head I6. Centrally of the arcuate plate 24 an axially extending, radially and outwardly projecting rib 21 is formed, which extends downwardly beyond the lowermost edge of the plate 24 forming a blade shank 28. The shank is extended inwardly and radially of the blade body forming an upper edge 29, which is as long approx mately as the top surface 2I of each slot in the bit head I6.

From the inner end of said edge 29, the inner edge of the shank extends longitudinally of the blade as at 30, and this edge 30 merges with the oblique inwardly extending edge 3|, of the blade tooth T. The length of the shank portion 28 of the blade projecting beyond the lowermost edge of the plate 24, is such that each bit head portion lying between the beveled surface I1 and the top surface 2| of each slot, may be inserted between the upper edge 29 and the beveled lower edge 26. The tooth T has a straight bottom cutting edge 32 which at its inner end merges with the upwardly and outwardly inclined edge 33 which joins the edge 3|. The lateral outer edge of the tooth is designated 34 and this is inset from and parallel with the outer longitudinal edge of the rib 21.

The three blades D are secured to the blade support II! by inserting the beveled bottom edges 26 of the blade plates 24 in the female beveled surface I! of the blade head I6 so that the head portions lying between the beveled top surface l7 and the horizontal top surfaces 2! of the head slots are located in the spaces between the beveled lower edges 26 of the blade plates 24 and the upper edges 29 on the blade shanks. The rearward surfaces of the shanks 28 of the blades will then abut the backing surfaces IQ of the slots and the forward directed faces of the shoulders 18. Then the sub 13 is screwed onto the blade support I6 so that the female lower beveled edge 15 of the bit sub engages the male beveled upper edge 25 of the blade plate 24 clamping said plate securely between the two female surfaces l and I l as described above. The space between the lowest part of the edge 26 and edge 29 issuificient to permit the edge 26 to be moved into position over the surface [1, at which time the edge 29 will be in close proximity to the top surface 21 of the head slot. The edge 26 is then seated on the surface 11 which will cause the surface 21 and edge 29 to separate as shown in Figure 3, but the inner part of the shank will remain in the slot to prevent movement of the blade around the support.

When the bit is assembled, the bit sub is is threadedly secured to the bore stem i4. Accumulated material cut by the blades may be Washed away bywater introduced in any preferred conventional manner into the bore 23 of the bit body D and flowing from there through the holes 22 in the bit body head 16.

Heretofore, the entire bit used to be made from an integral piece of steel or similar metal producing a comparatively heavy body, and when one of the cutting edges of the blades or a part thereof was damaged: or dulled, it was necessary to remove thebit from the sub or the stem of the drill to have it repaired. or sharpened. In the latter: operation, the weight of bulk of the entire bit had to be manipulated and supported, entailing unnecessary work and consuming unnecessary time; By using the above described bit, it is only necessary to remove and replace the damaged: blade, saving time, and labor, and when the damaged part has to be shipped for repair or anew oneorderedfor replacement, the shipping expense is considerably reduced on account of reduction of the necessary shipping weight and shipping space;

I claim: a

l'-. A drill bit comprising a blade support having' a long tubular member and a substantially semi-globular head on one end thereof, the head 4 having the rounded side directed downward and providing an upwardly facing part surrounding said member, said part having an inwardly beveled surface, a plurality of blades each comprising an arcuate plate, a blade shank extending from an end of the plate and a tooth integral with the shank, said shank having a top edge portion extending across and spaced from the adjacent end edge of the plate, said plate being formed to partly'encircle the tubular member and having said end edge formed to seat in said inwardly beveled surface, said head having a laterally and downwardly opening slot in said rounded side for each blade in which the said top edge of the shank engages, the head havin water discharge ports each adjacent to a side of a slot for discharge across the face of an adjacent tooth face, and a tubular coupling threaded on the other end of said tubular member.

2. A drill bit of the character stated in claim 1, wherein each blade tooth has an inwardly and downwardly sloping inner edge whereby the tooth is of gradually increasing width from the shank downwardly and the lower portion of each tooth extends inwardly to approximately the axial center of the blade support.

3, A drill bit of the character stated in claim 1, with a radially projecting shoulder formed integral with said head at one side of each slot and having a forwardly directed face against which the shank portion of the adjacent blade positions.

ERNEST S. CREEL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 832,779 Cushing Oct. 9', 1906 1,065,298 Currell June 17, 1913 1,370,492 Smith et a1 Mar. 1, 1921 1,392,702 Phillips Oct. 4, 1921 1,510,871 Swaim Oct. 7, 1924 1,786,414 Kennedye Dec. 23, 1930 1,881,024 Lang Oct. 4, 1932 2,009,742 Mitchell July 30, 1935 2,190,434 Pivoto Feb. 13, 1940 2,446,795 Trimble Aug. 10, 1948 

